The present invention relates to a chip feeder for conveying a carrier tape, in which electronic chips such as chip resisters, chip capacitors or IC chips are sealed, to supply the chips to a chip mounter.
FIG. 16 shows a chip mounter 1 that automatically mounts the electronic chips on an electronic circuit board 2. The chip mounter 1 is provided with a first X-table 3 that carries the electronic circuit board 2, a second X-table 4 on which a plurality of chip feeders 10 are mounted and a placement head 6 that is supported by an arm 5 upon the X-tables 2 and 3. The first and second X-tables 2 and 3 are movable in an X-direction in a horizontal plane. The placement head 6 moves along a Y-direction that is perpendicular to the X-direction in the horizontal plane and along a Z-direction that is a vertical direction.
The placement head 6 chucks the electronic chip selected from the chips supplied by the chip feeders 10 and places the chucked chip on a predetermined position of the electronic circuit board 2.
The chip feeder 10 supplies the electronic chips sealed in a carrier tape such that the placement head 6 is able to pick the chips. As shown in FIGS. 17A and 17B, a series of emboss portions 21 are formed on the carrier tape 20 along its length, and a series of sprocket holes 22 are formed next to the emboss portions 21. The emboss portion 21 is a closed-end hollow and the sprocket hole 22 is a through hole. Top openings of the emboss portions 22 are sealed by a top cover tape 23 to prevent drop out of the electronic chips 7. The carrier tape 20, which includes the electronic chips 7 and is sealed by the top cover tape 23, is provided to a user as a warped condition around a reel.
Each of the chip feeders 10 is provided with a tape feeding mechanism 10A and a cover peeling mechanism 10B as shown in FIG. 18. The tape feeding mechanism 10A is provided with a sprocket 11 that connects the sprocket holes 22 formed on the carrier tape 20. A worm wheel 12 is coaxially fixed to the sprocket 11. A DC motor 13 rotates a worm 14 that is connected by a coupling 13a, and then the worm 14 rotates the worm wheel 12 with the sprocket 11. In general, the sprocket 11 includes a ratchet mechanism to keep constant feeding pitch. The cover peeling mechanism 10B includes a peeling reel 15 to wind the top cover tape 23 and a DC motor 16 to drive the peeling reel 15. An output axis of the DC motor 16 is connected to a worm 17 through a coupling 16a, and a worm wheel 18a is connected with the worm 17. A gear 18b that is coaxially fixed to the worm wheel 18a meshes with an external gear around the peeling reel 15.
When the DC motor 13 of the tape feeding mechanism 10A is driven, the sprocket 11 rotates in the clockwise direction in FIG. 18, which transfers the carrier tape 20 in the rightward direction in the drawing. On the other hand, a peeling piece 19 is fixed to a base 10C of the chip feeder at the upstream from the sprocket 11 along the transmission of the carrier tape 20. The top cover tape 23 is folded back by the peeling piece 19 to be wound by the peeling reel 15. Therefore, when the DC motor 16 of the cover peeling mechanism 10B is driven, the peeling reel 15 rotates in the counterclockwise direction in FIG. 18 to wind the top cover tape 23 that is peeled from the carrier tape 20. The DC motors 13 and 16 are controlled to synchronize the feeding of the carrier tape 20 and the peeling of the top cover tape 23.
Since the number of the chip feeders 10 mounted on the chip mounter 1 corresponds the chip variations contained on the electronic circuit board 2, the number of the chip feeders 10 increases as the electronic circuit becomes complex. On the other hand, the width of the carrier tape 20 is determined by the packaged chip size. Thus, the width of the chip feeder 10 should not be too large with respect to the width of the carrier tape 20 in order to mount a large number of the chip feeders 10 in the limited mount space. For instance, the chip mounter, in which forty chip feeders are aligned, requires the width equal to or smaller than fifteen millimeters for the individual chip feeder.
However, the conventional chip feeder 10 is difficult to reduce the width because of the spindle type DC motors 13 and 16. Necessary rotation torque for the feeding and the peeling limits miniaturization of the DC motors. When the DC motor is arranged such that the spindle is perpendicular to the width direction as shown in FIG. 18, the diameter of the DC motor determines the width of the chip feeder, which avoids decreasing the width of the chip feeder. On the other hand, when the spindle is parallel to the width direction, the width is determined by the length of the motor body and the projected spindle, which also avoids decreasing the width of the chip feeder.
It is therefore an object of the present invention to provide a chip feeder for chip mounter, which is capable of decreasing a size in the width direction.
For the above object, according to the present invention, there is provided an improved chip feeder, which includes: a tape feeding mechanism for feeding a carrier tape that further includes a rotating connection member for connecting the carrier tape, a first motor for driving the rotating connection member and a first transmission mechanism for transmitting drive power of the first motor to the rotating connection member, and a cover peeling mechanism for peeling a top cover tape from the carrier tape that further includes a peeling reel for winding the top cover tape, a second motor for driving the peeling reel and a second transmission mechanism for transmitting drive power of the second motor to the peeling reel. The first and second motors are outer rotor motors each of which includes a cylindrical stator fixed to a base at an axial center side having exciter coils and pole pieces magnetized by the exciter coils, and a cylindrical rotor arranged around the stator with a predetermined gap, and the first and second transmission mechanisms are engaged with outer surfaces of the rotors.
With this construction, the first and second motors are outer rotor motors, which allows the reduction of the thickness of the motor portions, decreasing the width of the chip feeder.
The rotating connection member may comprise a sprocket that connects sprocket holes formed on the carrier tape.
Each of the rotors may include a cylindrical permanent magnet whose pole varies along the circumferential direction and a back yoke fixed around the permanent magnet. In such a case, the first and second transmission mechanisms engage the outer surfaces of the back yokes.
The second transmission mechanism preferably includes at least three orbital rollers that externally contact the rotor of the second motor, a pulley that externally contacts the orbital rollers and rotates around an coaxial axis with the rotor, and at least three holding rollers that externally contact the pulley and are rotatably supported by the base. In such a case, the second transmission mechanism transmits rotation of the pulley to the peeling reel.
The peeling reel may form a single-piece construction with the pulley or the peeling reel may be linked with the pulley through a reduction mechanism. The reduction mechanism includes, for example, a first internal gear formed on an internal surface of an extending portion of the pulley extended in an axial direction, at least three small-diameter idle gears that are rotatably supported by the base to engage with the first internal gear, a center gear that engages with the idle gears to be rotated around the coaxial axis with the rotor, a sun gear that forms a single-piece construction with the center gear while keeping a predetermined distance from the center gear in the axial direction, a second internal gear formed on an internal surface of a cylindrical member fixed to the base with being coaxial with the rotor, at least three planetary gears that externally connect to the sun gear and are inscribed in the second internal gear, a rotation drum that holds rotation axes of the planetary gears to be rotated around the coaxial rotation axis with the rotor. The peeling reel forms a single-piece construction with the rotation drum.
Further, the holding rollers may be pressure rollers to apply centripetal force to the pulley.
Still further, the peeling reel may consists of a first collar member that includes a cylinder portion to wind the top cover tape and one collar, and a second collar member that includes a cylinder portion to wind the top cover tape and the other collar. In such a case, the first collar member is engaged with the second transmission mechanism and the second collar member is connected with the first collar member.
This construction expands applicability of the peeling reel to various top cover tapes having different width by exchanging the second collar member.
When the top cover tape exceeds the applicable range of the above described peeling reel, a center axis member is fixed to the base to be coaxial with the rotor of the second motor, and a closed-end cylindrical supporting member is mounted on the center axis member. The supporting member has a bottom portion that is rotatably connected to the center axis member at the closed-end side, and the open-end side thereof is engaged with the cylinder portion of the first collar member. In such a case, the second collar member is fitted around the first collar member and the supporting member that are engaged to each other.
The presence of the supporting member stabilizes the winding operation of the peeling reel even if the width of the top cover tape is extremely large. If the supporting member is not applied, the peeling reel becomes a cantilever, which causes instability in the winding operation.
The cylinder portions of the first collar member and the supporting member may have rectangular coupling teethes on the open-ends thereof. In such a case, the first collar member and the supporting member are engaged due to connection of the rectangular coupling teethes.
The width of the peeling reel can be adjusted without exchanging the collar member. For this purpose, rectangular coupling teethes can be formed on the open-ends of the cylinder portions of the first and second collar members. The first and second collar members can be engaged due to connection of the rectangular coupling teethes.
The rectangular coupling teeth of one of the first and second collar members may have a projection that is projected in the circumferential direction, and the rectangular coupling teeth of the other of the first and second collar members may have a plurality of pits in which the projection snaps. It is preferable that the pits are aligned in the axial direction with a predetermined distance in accordance with a standardized width of the top cover tape.
In general, the chip feeder is provided with an initial position sensor for detecting an initial position of the feeder to inform the chip supply timing to the chip mounter. The first transmission mechanism may include a backlash rejecting pressure gear in a gear train between a detected gear that is a target of the initial position sensor and a driven gear that drives the rotating connection member. The rotation axis of the pressure gear is movable in its perpendicular direction and the rotation axis is pressured by a spring such that the pressure gear pushes the gear in the gear train at the detected gear side and the gear in the gear train at the driven gear side.
Further, at the initial setting, it is necessary to add the pressure to the pressure gear under the condition where the detected gear and the rotating connection member are fixed to initial positions, respectively. Thus, the detected gear and the rotating connection member preferably have pin insertion holes at off-center positions and the base preferably has pin holding holes to hold tip-ends of pins passing through the pin insertion holes.